The Ultra Slime is an enormous Slime boss summoned by using Dark Gel. Under extremely rare circumstances, the Ultra Slime may spawn naturally in an area where many Snow Blocks are present. The boss is more powerful if spawned in a Hardmode world.

The Ultra Slime attacks in two ways. Its primary attack is to jump into the player, causing direct melee damage. It also tends to spawn Blue Slimes and flaming Earth Slimes, which attack the player.

Notes

The Ultra Slime is spawned just beyond the left edge of the screen when the Dark Gel is used. If solid blocks are present in that area, the Ultra Slime will spawn inside those blocks and slowly attempt to wriggle into the open.

It may be stronger than Oracam in hardmode.

Bugs and Glitches

The Ultra Slime may enter a constant regenerative state when attacked, and eventually transform into the more powerful Hardmode version.

The Ultra Slime may not possess enhanced stats if spawned while Hardmode is active.